In-Band On-Channel (IBOC) broadcasting is an emerging Digital Audio Broadcasting (DAB) technology, developed by IBIQUITY DIGITAL, INC., that enables existing radio broadcasters to transmit digital data over current analog transmission frequencies. Such radio broadcasters commonly employ amplitude-modulated (AM) and frequency-modulated (FM) bands for the transmission of audio broadcast data. IBOC technology has the ability to create a “hybrid” signal that can simultaneously send both the analog and digital data. U.S. Pat. No. 5,757,854, incorporated in its entirety herein by reference, discusses these capabilities in greater detail.
Digital data may be digitally-formatted data or digitally compressed analog data. Digital data may include processing instructions for rendering visual and/or audio components on, for example, an IBOC receiver. Such processing instructions may be used to render synchronized visual components, such as text and images describing artist or song title information for currently-broadcast songs on the analog band, news headlines, traffic reports or other information that would be of interest to a radio listener. The digital data may include audio components for presenting selectable audio data.
In an IBOC network, IBOC receivers recognize analog and digital data broadcast by IBOC transmitters, and present such data to a user through a display and/or an audio output. The user may interact with the data and provide a response via the IBOC receiver to either a party operating the IBOC transmitter or a third party. Additional examples of digital data and its uses are described in co-pending U.S. patent application Ser. No. 09/839,451, assigned to the assignee of the present invention.
In order to accommodate these various IBOC network functionalities, a protocol for the assembly, transmission and synchronization of such digital data is described.